1. Field of the Invention
The invention relates to a muffler with a variable damping characteristic for pulsating gases.
2. Description of the Prior Art
German reference DE U 89 08 244 discloses an exhaust gas muffler with more than one outlet tube. One of the outlet tubes can be opened and closed by means of a valve. The corrugated tube is located in the interior of the muffler housing. The interior of the corrugated tube is connected to the inlet tube of the muffler via a pressure line. If pressure increases in the inlet tube of the muffler as motor speed rises, the corrugated tube becomes longer. To use this elongation for the purpose of opening the valve, a relatively complicated mechanical system is needed. Moreover, the differential pressure between the inlet tube of the muffler and the interior of the muffler housing is relatively slight, so that corrugated tubes with a large cross-section are needed to produce the required forces.
It is also disadvantageous that sealing an end tube in the manner disclosed in DE U 89 08 244 results in the creation of high-frequency noises due to the increased gas speed in the unsealed end tube. Such designs are therefore unanimously rejected by experts.